ANSWER
[tex]x = \sqrt{5} [/tex] units
EXPLANATION
Let the other leg be x units.
According to the Pythagoras Theorem, the sum of the squares of the two shorter legs should add up to the square of the hypotenuse.
This implies that,
[tex] {x}^{2} + {2}^{2} = {3}^{2} [/tex]
[tex]{x}^{2} + 4=9[/tex]
Group the constant terms,
[tex]{x}^{2}=9 - 4[/tex]
[tex]{x}^{2}=5[/tex]
Take square root.
[tex]x = \sqrt{5} [/tex]